Method of manufacturing a rotary switch



Nov. 19, 196s R. R. KRONE 3,411,201

METHOD OF MANUFACTURING A ROTARY SWITCH Filed oct. 2a, 196s i 2 sheets-sheet 1 :w1/I6 e@ s/f vi y 24 a 411'/ 12J/yg 2, 28h/ www1/f1 .24 28 /8 z8 24 28 /8 28 INVENTOR F 2 wcsse///{Mne y BY M7/#JM Nov. 19, 1968 R. R. KRoNE 3,411,201

METHOD 0F MANUFACTURING A ROTARY swITcH Filed Oct. 28, 1965 2 Sheets-Sheet 2 24 INVENTOR 5b @ge/ @v3/Wma BY M9/#MM United States Patent C) 3,411,201 METHOD OF MANUFACTURING A RGTARY SWITCH Russell R. Krone, 6613 N. Prospect, Oklahoma City, Sida. 73111 Filed Oct. 28, 1963, Ser. No. 319,222 6 Claims. (Cl. 29-597) ABSTRACT OF THE DISCLOSURE A rotary switch is formed from a plurality of integral members, each of which has a ring portion electrically interconnecting a plurality of electrically conductive Segments extending therefrom. Nonconductive material is molded between the conductive members so that the segments are spaced apart in electrically isolated relationship, yet form a substantially continuous comm-on outer surface of conductive material. The molded nonconductive material is recessed from the common outer surface of the segments, and may cover the inwardly facing surface of the ring portion of one or more of the members.

The present invention relates to electrical switches and more particularly, but not by way of limitation, relates to an improved rotary switch construction particularly adapted for use in the ignition system of internal combustion engines and to a method for manufacturing the switch.

It has long been recognized in the art that a rotary switch possesses many unique qualities of operation which are far superior to various types of switches employing opening and closing contacts. This is particularly true in internal combustion engine ignition systems wherein socalled points are used to interrupt an electrical circuit in timed sequence with operation of the engine in order to cause a spark fand ignite the fuel in the engine. The basic approach taken by prior workers in the art was to provide a rotating switch member having alternate conductive and non-conductive segments and a brush riding against the rotating switch. However, the prior art workers all utilized alternate plastic and metal segments and were totally unsuccessful. The present inventor discovered that all of the segments which contacted the brush must be electrically conductive, and accordingly described such an ignition system and rotary switch in U.S. Patent No. 3,087,000. However, before this type of switch could be made readily available to the public, not only for automobile ignition systems but for many other rotary switch applications, it Was necessary to find a better means for mass-producing the switches on a more economical basis. Therefore, the present invention is particularly related to an improved rotary switch of the type disclosed in the above-referenced patent, and to a method for economically fabricating the rotary switch on a mass production basis. However, it is to be understood that the present invention, in its broader aspects, is not restricted to ignition systems for internal combustion engines.

The present invention contemplates ra rotary switch member comprised of a plurality of electrically-conductive members, each having a plurality of segments with cylindrically-shaped outer surfaces. The segments of the various conductive members are spaced fone from the other and, in combination, form a common, cylindrical surface. The conductive members are interconnected and held in spaced, electrically-isloated positions by an electrically non-conductive member which will usually comprise a suitable plastic material.

The method of the present invention provides a means for fabricating the novel rotary switch comprising the steps of forming at least two integral members of electri- ICC cally-conductive material each having one or more segments which are disposable in predetermined relationship to form a common cylinder or other suitable surface, orienting the members in spaced relationship, and molding a non-conductive material between the members to hold the members in spaced, electrically-isolated relationship.

Therefore, it is an important object of the present invention to provide an improved rotary switch construction which can be mass-produced on an economical basis.

Another object of the present invention is to provide a method for mass-producing `a rotary electrical switch on an economical basis.

Still another object of the invention is to provide an improved rotary switch for replacing the breaker points of an automobile ignition system.

Another object of the present invention is to provide a rotary switch of the type described which may be quickly and easily installed in the ignition system of any one of the engines of the four major automobile manufacturers.

Yet another object of the invention is to provide a rotary switch of the type described having greater strength, particularly against centrifugal disintegration so that it can be operated :at high speeds.

Many additional objects and advantages will be evident to those skilled in the art from the following detailed description and drawings, wherein:

FIGURE l is a top View of a rotary switch constructed in accordance with the present invention;

FIGURE 2 is a side View of the rotary switch construction of FIGURE 1;

FIGURE 3 is a sectional view taken on lines 3--3 'of FIGURE 1;

FIGURE 4 is a sectional view taken on lines 4 4 of FIGURE l; and,

FIGURES 5a and 5b are perspective views of two component parts of the rotary switch of FIGURE l.

As previously mentioned, the present invention is related to the type of ignition system disclosed in my prior U.S. Patent No. 3,087,000, and accordingly, the embodiment which will presently be described is particularly adapted for use in connection with a standard distributor for an eight-cylinder internal combustion engine of the type used in automobiles as described in my patent. In this type of ignition system, a timing shaft 5 (shown in dotted outline) is driven in synchronism with the engine and is provided with a polygon-shaped cam 6 (shown in dotted outline) having a number of sides corresponding to the number of cylinders of the engine. For example, an eight-cylinder engine would have an Octagon-shaped cam as illustrated, while a six-cylinder engine would have a heXagon-shaped cam. The cam 6 normally actuates a set of mechanical breaker points which opens a circuit including a capacitor and the primary coil of a transformer and thereby induces a high voltage in the secondary Winding of the coil which is applied to the appropriate spark plug by a distributor arm which is also connected to and rotates with the timing shaft.

A rotary switch constructed in accordance with the present invention is placed around the polygonashaped cam 6 and one set of alternate segments of the switch are electrically connected to the cam, while the other alternate set of segments are electrically insulated from the cam as will presently be described. A brush 8 (shown in dotted outline) rides on the rotary switch. When the brush is in contact with the electrically-conductive segment, the circuit (not illustrated) including the primary transformer winding is completed and when the brush is in contact with the insulated segments, the circuit is broken to induce an impulse in the secondary Winding which is applied to the appropriate spark plug.

The rotary switch member is comprised of a rst electrically-conductive member, indicated generally by the reference numeral 12 (see FIGURE 5a), and a second electrically-conductive member, indicated generally by the reference numeral 14 (see FIGURE 5b). The member 12 is comprised of a ring portion 16 and a plurality of segment portions 18 each of which is connected to the ring portion 16 by a spacer portion 20. Each of the segments 18 has a cylindrical outer surface 18a. The outer surfaces of the several segments have a common radius of curvature and consequently lie within a common cylinder. The spacer portions 20 hold the cylindrically concave inner surfaces 18b of the segments at a greater radius than that of the outer surface 16a of the ring portion 16 and also at a greater radius than the outer surface of the ring portion of the member 14 so as to permit electrical isolation of the segments 18 from the member 14 as will presently be described in greater detail. The inner surface b of the ring portion 16 is also circular and of greater radius than any portion of the hexagonal cam on the timing shaft so that the member 12 may be electrically isolated from the cam 6 as will presently be described.

The member 14 is similar to the member 12 in that it is comprised of a ring portion 22 and a plurality of segments 24 each of which is connected to the ring portion 22 by spacer portions 26. The outer faces 24a of the segments 24 are also cylindrically shaped and have the same radius of curvature as the faces 18a, and all of the faces 24a lie in the same common cylinder as the faces 18a. The inner faces 24b of the segments 24 may conveniently be cylindrically concave and lie on the same radius as the inner faces 1811 of the segments 18 so as to be spaced from the other ring portion 16. Similarly, the outer radius 22a of the ring portion 22 is of substantially the same radius as the outer surface 16a of the ring portion 16. However, the two members differ in that the inner surface 22b of the ring portion 22 is octagonally shaped so as to receive the cam on the timing shaft rather than being round like the ring portion 16 which must be spaced from the cam. The spacing between the segments and ring portions can best be seen in FIGURES 3 and 4 wherein it is evident that thespacer portions 26 and provide the necessary separation between the segments 24 and 18, respectively, from the ring portions 16 and 22, respectively. Also, the segments 18 are circumferentially separated from the segments 24 as can best be seen in FIGURE l so that the two members 12 and 14 are not in structural contact at any point.

The lmembers 12 and 14 are interconnected and maintained in spaced relationship by a body of electrically non-conductive material 28 which effectively provides electrical isolation between the two-members. As can be seen in FIGURE l, the body of insulating material 28 also has an octagonal inner surface 28a corresponding to the octagonal inner surface 2211 of the member 14 and thereby forms an annular insulating ring portion 28b between the ring portion 16 and the cam onto which the rotary switch 10 is placed. The inner surface 28a of the resilient material 28 is also preferably provided with a plurality of very small projections 30 on each flat face of the octagonal inner surface. Each of the projections 30 may extend approximately 0.005 inch from the face, and the projections serve to accommodate the rotary switch 10 to the distributor for any one of the four major automobile manufacturers eight-cylinder engines. Since the non-conductive material 26 will usually be a relatively resilient plastic material as will presently be described, the projections 30 can be deformed by pressing the rotary switch down over the timing shaft cam 6 and will insure that the ring portion 32 of the fiat surface of the electrically-conductive member 14 will always engage the timing shaft cam 6 and thereby complete the electrical circuit.

In operation, the switch member 10 is placed over the cam 6 and the brush 8 is biased against the outer periphery of the switch member formed by the several segments 12 and 14. As the switch member is rotated by the cam, the primary electrical circuit is completed through the brush to each of the conductive segments 14 and then to the cam 6, which is electrical ground. The primary circuit is opened each time that the brush leaves the conductive segments 14 and contacts the electricallyisolated segments 12 and thereby induces a plus in the secondary circuit and fires the appropriate spark plug. In accordance with the method of the present invention, the members 12 and 14 are formed from an electricallyconductive material in such a manner as to provide a plurality of electrically-conductive segments each having an outer cylindrical surface which may be positioned in a common cylindrical or other suitable surface, yet which can be oriented in -completely spaced relationship. The preferred method of forming the members 12 and 14 is by sintering a mixture of copper and silver in the well-known and conventional manner. However, in its broader -aspects the method of the present invention includes cold extruding, stamping or any other means for forming the electrically-conductive members 12 and 14, or such other members as may be desired. In general, sintering entails mixing powdered copper and silver with a suitable binder, compressing the material in a mold at a very high pressure, and then firing the material to cause the binder to fuse and form a solid metal member.

After the members 12 and 14 have been formed, the two members are placed in a mold and maintained in spaced relationship while a suitable non-conductive material, such as nylon, is injected between the two members to form the mass of material 28 which interconnects the two members and maintains the members in spaced, electrically-isolated relationship. It will readily be appreciated that the members 12 and 14 are particularly well adapted to be retained in predetermined positions within an injection mold. For example, the octagonal inner shape of the ring portion 22 of the member 14 may be slipped over an octagonal core having the necessary recesses to form the projections 30. The cylindrical portion of the mold receiving the surfaces 18a and 24a may conveniently be provided with longitudinally extending ribs to both maintain the segments 18 and 24 properly separated and also prevent the mass of nonconductive material 28 from extending outward to the cylindrical surface formed by the outer faces 18a and 24a. From the above detailed description of a preferred embodiment of the present invention, it will be evident that a novel rotary switch construction has been described. Since all of the conductive segments are integral with an innterconnecting metal ring portion, the construction has a high strength against centrifugal disintegration, and it will be noted that the bond strength between the resilient material and the metal segments is not necessarily relied upon to hold the segments in place. Due to the novel construction of the interior of the rotary switch, a single sized element will fit any of the distributors of the four major automobile manufacturers. Production of the rotary switch can be substantially automated so that the switches can be mass-produced on a very economical basis in accordance with the method of the present invention.

Although the embodiment disclosed is a novel switch for use as a circuit interrupter in an internal combustion engine ignition system, it will be appreciated from the above disclosure that more than two conductive members having conductive segments lying in the cylinder formed by the outer faces can be employed, and that the conductive segments of the various members can be deployed in substantially any circumferential order. It is also to be understood that in accordance with the broader aspects of this invention, electrical contact with the various conductive segments can be made in any desired manner, rather than having a portion of the segments electrically connected to ground and a portion of the segments electrically insulated from ground as in the embodiment described.

The novel method for manufacturing the switch provides a means for producing the switch on a mass production basis by fully automated equipment and with great precision. In the broader aspects, the method can be used to manufacture switches having more than two sets of electrically-interconnected segments and in substantially any circumferential order.

Although a preferred embodiment of the invention has been described in detail, it is to be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. A method for manufacturing a rotary switch having a plurality of circumferentially spaced electricallyconductive peripheral segments comprising the steps of:

forming at least two members each having a plurality of electrically-conductive segments adapted to be oriented in a common surface, at least two of the electrically-conductive segments being electrically interconnected,

orienting the members in such a relationship that the electrically-conductive segments are disposed in a common surface and the members are spaced apart and electrically isolated, and

inserting an electrically non-conductive member between the members to maintain the conductive segments of the respective members in spaced, electrically-isolated relationship in the common surface.

2. A method for manufacturing a rotary switch comprising the steps defined in claim 1 wherein:

the electrically non-conductive member is molded between the other members.

3. A method for fabricating a rotary switch having a plurality of electrically-conductive peripheral segments comprising the steps of:

forming at least two integral members -of electrically-conductive material each having a plurality of lsegments adapted to be ydisposed in a common exposed surface with the members in spaced, electrically isolated relationship, and

molding a non-conductive material between the rnembers to hold the members in spaced, electricallyisolated relationship with the segments disposed in a common exposed surface with the nonconductive material recessed from the common surface.

4. A method for fabricating a rotary switch having a plurality of electrically-conductive peripheral segments comprising the steps of:

`forming at least two members of electrically-conductive material each of which has an interior ring portion and at least one peripheral segment portion, the segment portions of the members being disposable on a common radius in circumferentiallyspaced relationship to produce a substantially continuous exposed curvature,

positioning the members in spaced electrically isolated relationship with the peripheral segment portions being circumferentially spaced and forming a substantially continuous exposed curvature, and

molding a body of electrically non-conductive material between the members to hold the members in spaced electrically-isolated position with the electricallyconductive segments circumferentially spaced, and forming a substantially continuous curvature the nonconductive material being recessed from the curvature formed by the outer surface of the segments.

5. A method ifor fabricating a rotary switch for use on a polygon-shaped cam of an internal combustion engine ignition system as a circuit interrupter comprising the steps of:

forming iirst and second integral members of electrically-conductive material each having a ring portion and circumferentially-spaced peripheral segment portions adapted to be arranged in spaced relationship to form a generally continuous cylindrical surface, the ring portion of the first members having an interior surface of greater diameter than any portion of the cam and the ring portion of the second member having a polygon-shaped interior surface adapted to be placed over the carn,

placing the first and second members in a generally cylindrical mold having a polygon-shaped core corresponding to the size and shape of the interior surface of the ring portion of the second member and holding the two members in spaced relationship with the segment portions forming a substantially continuous cylindrical surface,

molding a body of non-conductive material between the members to hold the members in electricallyisolated relationship and between the first member and the core to provide electrical insulation between the lirst member and the cam.

6. A method for fabricating a rotary switch for use on a polygon shaped cam of an internal combustion engine ignition system as a circuit interrupter comprising the steps defined in claim 5 wherein:

the .first and second members are formed by sintering a conductive mixture, and

the electrically non-conductive material is injection molded between the members.

References Cited UNITED STATES PATENTS 2,696,658 12/1954 Polard 29--155.54 3,036,165 5 1962 Kallin et al 200-24 X 3,087,000 4/ 1963 Krone 200-24 X 3,243,872 4/1966 Henry-Baudet 29-155.53 2,902,552 9/ 1959 Oliveira 200-24 3,022,389 2/ 1962 Wolrab 200-24 3,163,923 1/1965 Lehmann et al 29-l55.55 3,167,852 2/1965 Stengl 29--l55.55

`lOHN F. CAMPBELL, Primary Examiner.

C. E. HALL, Assistant Examiner. 

